From 22d017e7ac287b612f7d4f45bb1357bec11f8c36 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Mon, 3 Oct 2022 09:10:49 -0700
Subject: [PATCH 1/7] start script to check exceptions only raise

---
 .pre-commit-config.yaml        |  6 ++++
 pandas/core/indexes/base.py    | 13 ++++++--
 scripts/no_return_exception.py | 59 ++++++++++++++++++++++++++++++++++
 3 files changed, 76 insertions(+), 2 deletions(-)
 create mode 100644 scripts/no_return_exception.py

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 039b3c4e4d86c..8bbdf87bf850d 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -226,6 +226,12 @@ repos:
         entry: python scripts/no_bool_in_generic.py
         language: python
         files: ^pandas/core/generic\.py$
+    -   id: no-return-exception
+        name: Raise Exceptions instead of Return
+        entry: python scripts/no_return_exception.py
+        language: python
+        files: ^pandas/
+        types: [python]
     -   id: pandas-errors-documented
         name: Ensure pandas errors are documented in doc/source/reference/testing.rst
         entry: python scripts/pandas_errors_documented.py
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 47e3314c6d9c3..014a52ccfd86e 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -4386,14 +4386,23 @@ def is_int(v):
         return indexer
 
     @final
-    def _invalid_indexer(self, form: str_t, key) -> TypeError:
+    def _invalid_indexer(
+        self,
+        form: str_t,
+        key,
+        reraise: lib.no_default | None | Exception = lib.no_default,
+    ) -> None:
         """
         Consistent invalid indexer message.
         """
-        return TypeError(
+        msg = (
             f"cannot do {form} indexing on {type(self).__name__} with these "
             f"indexers [{key}] of type {type(key).__name__}"
         )
+        if reraise is not lib.no_default:
+            raise TypeError(msg) from reraise
+        else:
+            raise TypeError(msg)
 
     # --------------------------------------------------------------------
     # Reindex Methods
diff --git a/scripts/no_return_exception.py b/scripts/no_return_exception.py
new file mode 100644
index 0000000000000..40eec5dd7dee4
--- /dev/null
+++ b/scripts/no_return_exception.py
@@ -0,0 +1,59 @@
+"""
+Check that functions return isn't use for Exception or its subclasses.
+
+This ensures public methods don't accidentally return exceptions instead of raising.
+
+This is meant to be run as a pre-commit hook - to run it manually, you can do:
+
+    pre-commit run no-return-exception --all-files
+
+"""
+from __future__ import annotations
+
+import argparse
+import ast
+import sys
+from typing import Sequence
+
+
+ERROR_MESSAGE = (
+    "{path}:{lineno}:{col_offset}: "
+    "Don't return an Exception subclass, raise it instead\n"
+)
+
+
+class Visitor(ast.NodeVisitor):
+    def __init__(self, path: str) -> None:
+        self.path = path
+
+    def visit_FunctionDef(self, node) -> None:
+        returns = node.returns
+        name = getattr(returns, "id", None)
+        exception_ends = ("Exit", "Interrupt", "Exception", "Error", "Iteration")
+        if name is not None and any(name.endswith(end) for end in exception_ends):
+            msg = ERROR_MESSAGE.format(
+                path=self.path, lineno=node.lineno, col_offset=node.col_offset
+            )
+            sys.stdout.write(msg)
+            sys.exit(1)
+
+
+def no_return_exception(content: str, path: str) -> None:
+    tree = ast.parse(content)
+    visitor = Visitor(path)
+    visitor.visit(tree)
+
+
+def main(argv: Sequence[str] | None = None) -> None:
+    parser = argparse.ArgumentParser()
+    parser.add_argument("paths", nargs="*")
+    args = parser.parse_args(argv)
+
+    for path in args.paths:
+        with open(path, encoding="utf-8") as fd:
+            content = fd.read()
+        no_return_exception(content, path)
+
+
+if __name__ == "__main__":
+    main()

From af8699932f18113841d6bc92268ce194a09e1b88 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Mon, 3 Oct 2022 09:11:07 -0700
Subject: [PATCH 2/7] start script to check exceptions only raise

---
 scripts/no_return_exception.py | 1 -
 1 file changed, 1 deletion(-)

diff --git a/scripts/no_return_exception.py b/scripts/no_return_exception.py
index 40eec5dd7dee4..b9bf61fba5404 100644
--- a/scripts/no_return_exception.py
+++ b/scripts/no_return_exception.py
@@ -15,7 +15,6 @@
 import sys
 from typing import Sequence
 
-
 ERROR_MESSAGE = (
     "{path}:{lineno}:{col_offset}: "
     "Don't return an Exception subclass, raise it instead\n"

From fe5a0acec34c16728f279383cc043cce0250c5d0 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Tue, 4 Oct 2022 16:16:00 -0700
Subject: [PATCH 3/7] Refactor function to raise

---
 pandas/core/indexes/base.py         | 8 ++++----
 pandas/core/indexes/datetimelike.py | 4 ++--
 2 files changed, 6 insertions(+), 6 deletions(-)

diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 014a52ccfd86e..333d5a0c3246f 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -4386,14 +4386,14 @@ def is_int(v):
         return indexer
 
     @final
-    def _invalid_indexer(
+    def _raise_invalid_indexer(
         self,
         form: str_t,
         key,
         reraise: lib.no_default | None | Exception = lib.no_default,
     ) -> None:
         """
-        Consistent invalid indexer message.
+        Raise consistent invalid indexer message.
         """
         msg = (
             f"cannot do {form} indexing on {type(self).__name__} with these "
@@ -6691,7 +6691,7 @@ def _validate_indexer(self, form: str_t, key, kind: str_t):
         assert kind in ["getitem", "iloc"]
 
         if key is not None and not is_integer(key):
-            raise self._invalid_indexer(form, key)
+            self._raise_invalid_indexer(form, key)
 
     def _maybe_cast_slice_bound(self, label, side: str_t, kind=no_default):
         """
@@ -6723,7 +6723,7 @@ def _maybe_cast_slice_bound(self, label, side: str_t, kind=no_default):
         # datetimelike Indexes
         # reject them, if index does not contain label
         if (is_float(label) or is_integer(label)) and label not in self:
-            raise self._invalid_indexer("slice", label)
+            self._raise_invalid_indexer("slice", label)
 
         return label
 
diff --git a/pandas/core/indexes/datetimelike.py b/pandas/core/indexes/datetimelike.py
index 147d1649e5e1b..e3d766709f52f 100644
--- a/pandas/core/indexes/datetimelike.py
+++ b/pandas/core/indexes/datetimelike.py
@@ -314,12 +314,12 @@ def _maybe_cast_slice_bound(self, label, side: str, kind=lib.no_default):
                 # DTI -> parsing.DateParseError
                 # TDI -> 'unit abbreviation w/o a number'
                 # PI -> string cannot be parsed as datetime-like
-                raise self._invalid_indexer("slice", label) from err
+                self._raise_invalid_indexer("slice", label, err)
 
             lower, upper = self._parsed_string_to_bounds(reso, parsed)
             return lower if side == "left" else upper
         elif not isinstance(label, self._data._recognized_scalars):
-            raise self._invalid_indexer("slice", label)
+            self._raise_invalid_indexer("slice", label)
 
         return label
 

From 1f7bb4342c3038c493aa811b507edc6dc8f0c197 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Tue, 4 Oct 2022 17:07:38 -0700
Subject: [PATCH 4/7] Use pygrep instead of script

---
 .pre-commit-config.yaml           |  7 ++--
 pandas/core/indexes/base.py       |  8 ++---
 pandas/core/indexes/category.py   |  2 +-
 pandas/core/indexes/datetimes.py  |  2 +-
 pandas/core/indexes/numeric.py    |  2 +-
 pandas/core/indexes/period.py     |  2 +-
 pandas/core/indexes/timedeltas.py |  2 +-
 pandas/core/internals/managers.py | 14 ++++----
 pandas/io/pytables.py             | 17 +++++----
 scripts/no_return_exception.py    | 58 -------------------------------
 10 files changed, 28 insertions(+), 86 deletions(-)
 delete mode 100644 scripts/no_return_exception.py

diff --git a/.pre-commit-config.yaml b/.pre-commit-config.yaml
index 157f753a1c83b..8d1d45a1f0909 100644
--- a/.pre-commit-config.yaml
+++ b/.pre-commit-config.yaml
@@ -227,11 +227,12 @@ repos:
         language: python
         files: ^pandas/core/generic\.py$
     -   id: no-return-exception
-        name: Raise Exceptions instead of Return
-        entry: python scripts/no_return_exception.py
-        language: python
+        name: Use raise instead of return for exceptions
+        language: pygrep
+        entry: 'return [A-Za-z]+(Error|Exit|Interrupt|Exception|Iteration)'
         files: ^pandas/
         types: [python]
+        exclude: ^pandas/tests/
     -   id: pandas-errors-documented
         name: Ensure pandas errors are documented in doc/source/reference/testing.rst
         entry: python scripts/pandas_errors_documented.py
diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 333d5a0c3246f..583d8a1fd37e9 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -554,7 +554,7 @@ def __new__(
             return klass._simple_new(arr, name)
 
         elif is_scalar(data):
-            raise cls._scalar_data_error(data)
+            cls._raise_scalar_data_error(data)
         elif hasattr(data, "__array__"):
             return Index(np.asarray(data), dtype=dtype, copy=copy, name=name, **kwargs)
         else:
@@ -5288,10 +5288,10 @@ def where(self, cond, other=None) -> Index:
     # construction helpers
     @final
     @classmethod
-    def _scalar_data_error(cls, data):
+    def _raise_scalar_data_error(cls, data):
         # We return the TypeError so that we can raise it from the constructor
         #  in order to keep mypy happy
-        return TypeError(
+        raise TypeError(
             f"{cls.__name__}(...) must be called with a collection of some "
             f"kind, {repr(data)} was passed"
         )
@@ -6683,7 +6683,7 @@ def _maybe_cast_listlike_indexer(self, target) -> Index:
         return ensure_index(target)
 
     @final
-    def _validate_indexer(self, form: str_t, key, kind: str_t):
+    def _validate_indexer(self, form: str_t, key, kind: str_t) -> None:
         """
         If we are positional indexer, validate that we have appropriate
         typed bounds must be an integer.
diff --git a/pandas/core/indexes/category.py b/pandas/core/indexes/category.py
index d1bdedee5caa0..92c9cc1500962 100644
--- a/pandas/core/indexes/category.py
+++ b/pandas/core/indexes/category.py
@@ -230,7 +230,7 @@ def __new__(
             data = []
 
         if is_scalar(data):
-            raise cls._scalar_data_error(data)
+            cls._raise_scalar_data_error(data)
 
         data = Categorical(
             data, categories=categories, ordered=ordered, dtype=dtype, copy=copy
diff --git a/pandas/core/indexes/datetimes.py b/pandas/core/indexes/datetimes.py
index 99571de85561e..c0e3507dbab0b 100644
--- a/pandas/core/indexes/datetimes.py
+++ b/pandas/core/indexes/datetimes.py
@@ -334,7 +334,7 @@ def __new__(
     ) -> DatetimeIndex:
 
         if is_scalar(data):
-            raise cls._scalar_data_error(data)
+            cls._raise_scalar_data_error(data)
 
         # - Cases checked above all return/raise before reaching here - #
 
diff --git a/pandas/core/indexes/numeric.py b/pandas/core/indexes/numeric.py
index 946a6b818d4d4..186e45e6f4932 100644
--- a/pandas/core/indexes/numeric.py
+++ b/pandas/core/indexes/numeric.py
@@ -140,7 +140,7 @@ def _ensure_array(cls, data, dtype, copy: bool):
         if not isinstance(data, (np.ndarray, Index)):
             # Coerce to ndarray if not already ndarray or Index
             if is_scalar(data):
-                raise cls._scalar_data_error(data)
+                cls._raise_scalar_data_error(data)
 
             # other iterable of some kind
             if not isinstance(data, (ABCSeries, list, tuple)):
diff --git a/pandas/core/indexes/period.py b/pandas/core/indexes/period.py
index 5fb98b3bcd234..41a9fc8fa8e21 100644
--- a/pandas/core/indexes/period.py
+++ b/pandas/core/indexes/period.py
@@ -240,7 +240,7 @@ def __new__(
             # range-based.
             if not fields:
                 # test_pickle_compat_construction
-                raise cls._scalar_data_error(None)
+                cls._raise_scalar_data_error(None)
 
             data, freq2 = PeriodArray._generate_range(None, None, None, freq, fields)
             # PeriodArray._generate range does validation that fields is
diff --git a/pandas/core/indexes/timedeltas.py b/pandas/core/indexes/timedeltas.py
index f41e82897c208..eba7d79132e0b 100644
--- a/pandas/core/indexes/timedeltas.py
+++ b/pandas/core/indexes/timedeltas.py
@@ -128,7 +128,7 @@ def __new__(
         name = maybe_extract_name(name, data, cls)
 
         if is_scalar(data):
-            raise cls._scalar_data_error(data)
+            cls._raise_scalar_data_error(data)
 
         if unit in {"Y", "y", "M"}:
             raise ValueError(
diff --git a/pandas/core/internals/managers.py b/pandas/core/internals/managers.py
index 5a398533e1510..f3b7af0ea819d 100644
--- a/pandas/core/internals/managers.py
+++ b/pandas/core/internals/managers.py
@@ -1038,7 +1038,7 @@ def _verify_integrity(self) -> None:
         tot_items = sum(len(x.mgr_locs) for x in self.blocks)
         for block in self.blocks:
             if block.shape[1:] != mgr_shape[1:]:
-                raise construction_error(tot_items, block.shape[1:], self.axes)
+                raise_construction_error(tot_items, block.shape[1:], self.axes)
         if len(self.items) != tot_items:
             raise AssertionError(
                 "Number of manager items must equal union of "
@@ -2145,7 +2145,7 @@ def create_block_manager_from_blocks(
     except ValueError as err:
         arrays = [blk.values for blk in blocks]
         tot_items = sum(arr.shape[0] for arr in arrays)
-        raise construction_error(tot_items, arrays[0].shape[1:], axes, err)
+        raise_construction_error(tot_items, arrays[0].shape[1:], axes, err)
 
     if consolidate:
         mgr._consolidate_inplace()
@@ -2172,13 +2172,13 @@ def create_block_manager_from_column_arrays(
         blocks = _form_blocks(arrays, consolidate)
         mgr = BlockManager(blocks, axes, verify_integrity=False)
     except ValueError as e:
-        raise construction_error(len(arrays), arrays[0].shape, axes, e)
+        raise_construction_error(len(arrays), arrays[0].shape, axes, e)
     if consolidate:
         mgr._consolidate_inplace()
     return mgr
 
 
-def construction_error(
+def raise_construction_error(
     tot_items: int,
     block_shape: Shape,
     axes: list[Index],
@@ -2198,10 +2198,10 @@ def construction_error(
     # We return the exception object instead of raising it so that we
     #  can raise it in the caller; mypy plays better with that
     if passed == implied and e is not None:
-        return e
+        raise e
     if block_shape[0] == 0:
-        return ValueError("Empty data passed with indices specified.")
-    return ValueError(f"Shape of passed values is {passed}, indices imply {implied}")
+        raise ValueError("Empty data passed with indices specified.")
+    raise ValueError(f"Shape of passed values is {passed}, indices imply {implied}")
 
 
 # -----------------------------------------------------------------------
diff --git a/pandas/io/pytables.py b/pandas/io/pytables.py
index 6836420483a24..d93590e750c85 100644
--- a/pandas/io/pytables.py
+++ b/pandas/io/pytables.py
@@ -1658,13 +1658,6 @@ def _create_storer(
         if value is not None and not isinstance(value, (Series, DataFrame)):
             raise TypeError("value must be None, Series, or DataFrame")
 
-        def error(t):
-            # return instead of raising so mypy can tell where we are raising
-            return TypeError(
-                f"cannot properly create the storer for: [{t}] [group->"
-                f"{group},value->{type(value)},format->{format}"
-            )
-
         pt = _ensure_decoded(getattr(group._v_attrs, "pandas_type", None))
         tt = _ensure_decoded(getattr(group._v_attrs, "table_type", None))
 
@@ -1699,7 +1692,10 @@ def error(t):
             try:
                 cls = _STORER_MAP[pt]
             except KeyError as err:
-                raise error("_STORER_MAP") from err
+                raise TypeError(
+                    f"cannot properly create the storer for: [_STORER_MAP] [group->"
+                    f"{group},value->{type(value)},format->{format}"
+                ) from err
             return cls(self, group, encoding=encoding, errors=errors)
 
         # existing node (and must be a table)
@@ -1732,7 +1728,10 @@ def error(t):
         try:
             cls = _TABLE_MAP[tt]
         except KeyError as err:
-            raise error("_TABLE_MAP") from err
+            raise TypeError(
+                f"cannot properly create the storer for: [_TABLE_MAP] [group->"
+                f"{group},value->{type(value)},format->{format}"
+            ) from err
 
         return cls(self, group, encoding=encoding, errors=errors)
 
diff --git a/scripts/no_return_exception.py b/scripts/no_return_exception.py
deleted file mode 100644
index b9bf61fba5404..0000000000000
--- a/scripts/no_return_exception.py
+++ /dev/null
@@ -1,58 +0,0 @@
-"""
-Check that functions return isn't use for Exception or its subclasses.
-
-This ensures public methods don't accidentally return exceptions instead of raising.
-
-This is meant to be run as a pre-commit hook - to run it manually, you can do:
-
-    pre-commit run no-return-exception --all-files
-
-"""
-from __future__ import annotations
-
-import argparse
-import ast
-import sys
-from typing import Sequence
-
-ERROR_MESSAGE = (
-    "{path}:{lineno}:{col_offset}: "
-    "Don't return an Exception subclass, raise it instead\n"
-)
-
-
-class Visitor(ast.NodeVisitor):
-    def __init__(self, path: str) -> None:
-        self.path = path
-
-    def visit_FunctionDef(self, node) -> None:
-        returns = node.returns
-        name = getattr(returns, "id", None)
-        exception_ends = ("Exit", "Interrupt", "Exception", "Error", "Iteration")
-        if name is not None and any(name.endswith(end) for end in exception_ends):
-            msg = ERROR_MESSAGE.format(
-                path=self.path, lineno=node.lineno, col_offset=node.col_offset
-            )
-            sys.stdout.write(msg)
-            sys.exit(1)
-
-
-def no_return_exception(content: str, path: str) -> None:
-    tree = ast.parse(content)
-    visitor = Visitor(path)
-    visitor.visit(tree)
-
-
-def main(argv: Sequence[str] | None = None) -> None:
-    parser = argparse.ArgumentParser()
-    parser.add_argument("paths", nargs="*")
-    args = parser.parse_args(argv)
-
-    for path in args.paths:
-        with open(path, encoding="utf-8") as fd:
-            content = fd.read()
-        no_return_exception(content, path)
-
-
-if __name__ == "__main__":
-    main()

From 53e0f72e12e328c3025412fbdb4ec9359728a331 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 5 Oct 2022 09:59:12 -0700
Subject: [PATCH 5/7] Fix typing

---
 pandas/core/indexes/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 583d8a1fd37e9..0a0ede0242e81 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -4390,7 +4390,7 @@ def _raise_invalid_indexer(
         self,
         form: str_t,
         key,
-        reraise: lib.no_default | None | Exception = lib.no_default,
+        reraise: lib.NoDefault | None | Exception = lib.no_default,
     ) -> None:
         """
         Raise consistent invalid indexer message.

From 3e2c54b77de0b8e795b7808f32c4a9dd6f688659 Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 5 Oct 2022 11:40:30 -0700
Subject: [PATCH 6/7] Rase

---
 pandas/core/indexes/base.py | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index 0a0ede0242e81..eed1d648865bb 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -554,7 +554,7 @@ def __new__(
             return klass._simple_new(arr, name)
 
         elif is_scalar(data):
-            cls._raise_scalar_data_error(data)
+            raise cls._raise_scalar_data_error(data)
         elif hasattr(data, "__array__"):
             return Index(np.asarray(data), dtype=dtype, copy=copy, name=name, **kwargs)
         else:
@@ -5288,7 +5288,7 @@ def where(self, cond, other=None) -> Index:
     # construction helpers
     @final
     @classmethod
-    def _raise_scalar_data_error(cls, data):
+    def _raise_scalar_data_error(cls, data) -> None:
         # We return the TypeError so that we can raise it from the constructor
         #  in order to keep mypy happy
         raise TypeError(

From 0efdede0902e2bf0d91019419811c27b095e7edb Mon Sep 17 00:00:00 2001
From: Matthew Roeschke <10647082+mroeschke@users.noreply.github.com>
Date: Wed, 5 Oct 2022 15:07:06 -0700
Subject: [PATCH 7/7] Fix typing

---
 pandas/core/indexes/base.py | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/pandas/core/indexes/base.py b/pandas/core/indexes/base.py
index eed1d648865bb..5bbdca9b71ee3 100644
--- a/pandas/core/indexes/base.py
+++ b/pandas/core/indexes/base.py
@@ -5288,7 +5288,7 @@ def where(self, cond, other=None) -> Index:
     # construction helpers
     @final
     @classmethod
-    def _raise_scalar_data_error(cls, data) -> None:
+    def _raise_scalar_data_error(cls, data):
         # We return the TypeError so that we can raise it from the constructor
         #  in order to keep mypy happy
         raise TypeError(